The Occupational Studies Section conducts a wide-ranging program of epidemiologic studies to identify the occupational causes of cancer. Currently under investigation include studies of pesticides, benzene, methylene chloride, acrylonitrile, formaldehyde, asbestos, silica, phenol, combustion products, and methodologic investigations to improve exposure assessments. Occupational groups with complex exposures include jewelry manufacturers, laboratory workers, farmers, industrial workers in Turkey, pesticide applicators, embalmers, and workers exposed to benzene, acrylonitrile, and benzidine. Studies of agricultural-related occupa- tions uncovered elevated risks for lymphatic and hematopoietic cancer among farmers. Non-Hodgkin's lymphoma among farmers was strongly associated with use of the herbicide, 2,4-D. Leukemia was associated with several insecticides, particularly if used on animals. Leukemia, non-Hodgkin's lymphoma and nasopharyngeal cancer were elevated among embalmers and funeral directors (among blacks as well as whites) exposed to formaldehyde, while multiple myeloma and non-Hodgkin's lymphoma were associated with solvent exposure among aircraft maintenance workers, particularly among women. An excess of lung cancer among industrial workers exposed to formaldehyde occurred primarily in resin-producing plants and appeared to be due to chemicals other than formaldehyde. Lung cancer was also excessive among silicotics previously employed in the dusty trades in North Carolina. Total mortality, cancer and arteriosclerotic heart disease were greater among workers employed less than one year at the plant than among those employed longer, a phenomenon noted in other studies. This mortality difference appears to be due to lifestyle differences because short-term workers were not assigned to jobs with more intense exposures.